Network Address Port Translation - Nokia M1122 User Manual

M1122 User Manual
D
RFC2364 Virtual circuit multiplexed PPP over AAL5 (PPP-VC)
D
RFC2364 Virtual circuit multiplexed PPP over AAL5 used to
tunnel LAN/VBRIDGE PPTP packets
(TUNNELED-PPP-VC)
If an IP address is given to a virtual channel interface and bridging is
enabled at that interface, then IP data at that interface is routed and all
other protocols are bridged. The only encapsulation which allows both
bridging and routing simultaneously is ETH-LLC. For example, it is
possible to route ETH-LLC encapsulated packets and at the same time
bridge, for example, PPPoE packets (PPPoE packets are transported
directly over Ethernet frame, not within IP packets).
4.2 Routing
Routing is based on routing entries in a routing table. Static routes are
added via the management interface and dynamic routing is done using
RIP and RIPv2. Routing is done between the Ethernet 10Base-T
interface and the virtual channel connection (VCC) of the ATM/ADSL
interface. M1122 supports up to 8 simultaneous VCCs.
M1122 supports IGMP (Internet Group Management Protocol) proxy
receive function for IP multicast applications.
4.3 Bridging
Bridging is supported to provide full protocol transparency. Bridging
can be used simultaneously with IP routing. M1122 works as a
self-learning bridge supporting up to 1024 MAC addresses. Bridging
is done between the Ethernet 10Base-T interface and each ATM VCC
interface. Optionally, the bridging between the VCCs can be disabled.
4.4

Network Address Port Translation

M1122 supports Network Address Port Translation (NAPT) for
TCP/IP, UDP/IP and ICMP/IP protocols. When NAPT is used, a single
IP address is allocated to a VCC which leads to the public IP network.
The Ethernet subnet has private IP addressing and is not visible to the
VCC. NAPT translates the IP source address and source port number
dynamically to the VCC IP address and port number. Similarly,
packets coming from the VCC are mapped back to the original
destination addresses. NAPT allows up to hundreds of hosts to share a
18
E Copyright Nokia Networks Oy
C33906002SE_00